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ImgFS: a transparent cryptography for stored images using a filesystem in userspace

Osama A. KHASHAN,Abdullah M. ZIN,Elankovan A. SUNDARARAJAN

《信息与电子工程前沿（英文）》 2015年第16卷第1期页码 28-42 doi: 10.1631/FITEE.1400133

摘要： Real-time encryption and decryption of digital images stored on end-user devices is a challenging task due to the inherent features of the images. Traditional software encryption applications generally suffered from the expense of user convenience, performance efficiency, and the level of security provided. To overcome these limitations, the concept of transparent encryption has been proposed. This type of encryption mechanism can be implemented most efficiently with kernel file systems. However, this approach has some disadvantages since developing a new file system and attaching it in the kernel level requires a deep understanding of the kernel internal data structure. A filesystem in userspace (FUSE) can be used to bridge the gap. Nevertheless, current implementations of cryptographic FUSE-based file systems suffered from several weaknesses that make them less than ideal for deployment. This paper describes the design and implementation of ImgFS, a fully transparent cryptographic file system that resides on user space. ImgFS can provide a sophisticated way to access, manage, and monitor all encryption and key management operations for image files stored on the local disk without any interaction from the user. The development of ImgFS has managed to solve weaknesses that have been identified on cryptographic FUSE-based implementations. Experiments were carried out to measure the performance of ImgFS over image files’ read and write against the cryptographic service, and the results indicated that while ImgFS has managed to provide higher level of security and transparency, its performance was competitive with other established cryptographic FUSE-based schemes of high performance.

关键词： Storage image security Cryptographic file system Filesystem in userspace (FUSE) Transparent encryption

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Numerical study of the cyclic load behavior of AISI 316L stainless steel shear links for seismic fuse

Ruipeng LI,Yunfeng ZHANG,Le-Wei TONG

《结构与土木工程前沿（英文）》 2014年第8卷第4期页码 414-426 doi: 10.1007/s11709-014-0276-4

摘要： This paper presents the results of nonlinear finite element analyses conducted on stainless steel shear links. Stainless steels are attractive materials for seismic fuse device especially for corrosion-aware environment such as coastal regions because they are highly corrosion resistant, have good ductility and toughness properties in combination with low maintenance requirements. This paper discusses the promising use of AISI 316L stainless steel for shear links as seismic fuse devices. Hysteresis behaviors of four stainless steel shear link specimens under reversed cyclic loading were examined to assess their ultimate strength, plastic rotation and failure modes. The nonlinear finite element analysis results show that shear links made of AISI 316L stainless steel exhibit a high level of ductility. However, it is also found that because of large over-strength ratio associated with its strain hardening process, mixed shear and flexural failure modes were observed in stainless steel shear links compared with conventional steel shear links with the same length ratio. This raises the issue that proper design requirements such as length ratio, element compactness and stiffener spacing need to be determined to ensure the full development of the overall plastic rotation of the stainless steel shear links.

关键词： hysteretic damper eccentrically braced frame energy dissipation seismic stainless steel shear link

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Parametric computational study on butterfly-shaped hysteretic dampers

Ali Reza FARZAMPOUR, Matthew Roy EATHERTON

《结构与土木工程前沿（英文）》 2019年第13卷第5期页码 1214-1226 doi: 10.1007/s11709-019-0550-6

摘要： A parametric computational study is conducted to investigate the shear yielding, flexural yielding, and lateral torsional buckling limit states for butterfly-shaped links. After validating the accuracy of the finite element (FE) modeling approach against previous experiments, 112 computational models with different geometrical properties were constructed and analyzed including consideration of initial imperfections. The resulting yielding moment, corresponding critical shear force, the accumulation of plastic strains through the length of links as well as the amount of energy dissipated are investigated. The results indicate that as the shape of the butterfly-shaped links become too straight or conversely too narrow in the middle, peak accumulated plastic strains increase. The significant effect of plate thickness on the buckling limit state is examined in this study. Results show that overstrength for these links (peak force divided by yield force) is between 1.2 and 4.5, with straight links producing larger overstrength. Additionally, proportioning the links to delay buckling, and designing the links to yield in the flexural mode are shown to improve energy dissipation.

关键词： structural fuse hysteretic damper finite element analysis energy dissipation initial imperfection butterfly-shaped links

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Fused structures for safer and more economical constructions

Yu-Fei WU, Ying-Wu ZHOU, Biao HU, Xiaoxu HUANG, Scott SMITH

《结构与土木工程前沿（英文）》 2020年第14卷第1期页码 1-9 doi: 10.1007/s11709-019-0541-7

摘要： Safety margin and construction costs are two conflicting goals for a structure. By providing a fuse in a structure that is triggered at a certain level of over-loading, further increase of loading is prohibited and failure of the structure is changed to a safer mode. As overloading is controlled and a safer failure mode is enforced, a fused structure requires a smaller safety factor thus leading to more economical construction without compromising safety. The use of a fuse will also facilitate safer use of advanced construction materials such as fiber-reinforced polymer (FRP) composites. In this case, a fuse can transfer the sudden and dangerous failure mode associated with brittle FRP debonding or rupture to a safe and ductile failure mode at the fuse location. This paper introduces a new type of fused structure as well as an associated design philosophy and approach, in addition to examples of engineering applications.

关键词： fused structures structural fuse fiber-reinforced polymer concrete